Although the storm surge is perhaps the most dangerous and destructive part of a hurricane, the winds and the heavy rains can be felt well inland from a storm's landfall.
Rainfall Induced Flooding
The heavy rains associated with a tropical weather system are responsible not only for major flooding in areas where the storm initially strikes, but can also affect areas hundreds of miles from where the storm originally made landfall.
During landfall, it is not uncommon for 5 to 10 inches to fall. If it is large and moving slowly, rainfall could be even more excessive. As the storm moves inland, and is down graded to a tropical depression, the continued circulation, tropical moisture, and topography can contribute to copious amounts of rainfall.
While Hurricane Camille devastated the coast of Mississippi on landfall in 1969, the storm moved inland, flooding areas of Kentucky, West Virginia, and Virginia. Almost half of the 256 people killed by Camille died in floods away from the coast.
Intense flooding can also occur from tropical depressions and storms that do not reach the intensity levels associated with hurricanes.
After Tropical Storm Alberto made landfall near Destin, Florida, on July 3, 1994, residents and summer vacationers breathed a sigh if relief. The storm, packing sustained winds of 55 knots, never reached hurricane proportions. Damage on the coast was generally minor, and except for some disruption of pre-Fourth of July activities, life returned to its usual course.
However, Alberto's destruction was just beginning. For four days, the storm lazily lingered over eastern Alabama and western Georgia, deluging the area with torrential rains. It caused widespread flooding of both the Flint and Ocmulgee Rivers in Georgia. Americus, Georgia, was particularly hard hit.
A record breaking twenty-one inches of rain fell in a 24-hour period. Macon, Georgia, also suffered Alberto's relentless rains, as over ten inches of rain were recorded over the same period.
The heavy rains and floods associated with Alberto proved costly. Over $500 million of property damage was reported in connection with the storm. Twenty-eight people in Georgia and two in Alabama lost their lives.
The storm surge is a rapid rise in the level of the water that moves onto land as the eye of the storm makes landfall. Generally speaking, the stronger the hurricane, the greater the storm surge.
As a hurricane approaches the coast, its winds drive water toward the shore. Once the edge of the storm reaches the shallow waters of the continental shelf, the water piles up. Winds of hurricane strength force the water onto the shore.
At first, the water level climbs slowly, but as the eye of the storm approaches, water rises rapidly. Wave after wave hits the coast as tons of moving water hammer away at any structure built on the coastline.
"A cubic yard of water weighs about 1700 pounds and it's almost incompressible," says John Hope, Tropical Coordinator at The Weather Channel. "You might just as well be hit with a solid object as to have this water smashing against a structure on a beach."
The surge is greater if a hurricane's track is perpendicular to the coastline, allowing the surge to build higher. The storm surge is also greater if the storm affects a bay or if it makes landfall at high tide. The greatest storm surge occurs to the right of where the eye makes landfall.
In 1969, Hurricane Camille's storm surge was a record 24 1/2 above sea level at Pass Christian, Mississippi. The Richelieu Apartment complex, located near the shoreline, was a three-story concrete structure. As Camille approached, twenty-five residents refused to evacuate. Instead, they threw a "hurricane" party in Camille's honor. Camille's storm surge destroyed the complex and only two people survived the storm.
Because of that tragedy, emergency management authorities and local governments have improved their procedures on public awareness and for issuing evacuations. Working in coordination with the National Hurricane Center (NHC), watches and warnings are disseminated in a more timely manner to the public.
The winds of a hurricane range from 74 miles per hour (65 knots) in a minimal storm to greater than 155 miles per hour (136 knots) in a catastrophic one. Often accurate readings of high wind gusts during landfall are impossible because the anemometers at reporting wind stations are ripped from their foundations.
Wind is responsible for much of the structural damage caused by hurricanes. High winds uproot trees and tear down power lines. The maximum winds from fast moving and powerful storms may remain high, even when the storm is well inland. Often this is actual wind speed combined with the speed of the storm.
For example, Hurricane Hazel moved through western New York on October 15, 1954, giving Buffalo winds near 100 miles per hour.
Check how geography plays a part in the extent of damage a land falling hurricane can cause.